Sharpstar Optics 2.5" Field Flattener - FF25L

This field flattener is suitable for most doublets and triplets from f/5 to f/9. 

Please see the back focus chart for recommended spacing for given focal lengths.

The flattener has a male M68 thread and will attach to any focuser that uses a female M68 thread.  Adapters can be used for other thread sizes.

SharpStar have designed this flattener with a long back focus distance to facilitate the use of accessories such as Off Axis Guiders, Filter Wheels etc. 

Specifications

Field flattener for f/5 - f/9 refractors
Full aperture: 61.5mm
Thread on camera side: M69 female
Threads on telescope side: M68 male and M63 female
Fully multi-coated optical surfaces
Blackened interior for improved reflection suppression
Recommended distance between camera side thread and focal plane: 91.5mm
M48 adapter with 36.5mm length included (to create 55mm back focus from adapter to camera sensor)
Overall Length: 79.7mm